The invention relates to traction roller transmissions in which motion is transmitted from an input to an output shaft by traction rollers arranged between, and in engagement with, toric discs mounted opposite each other on the input and output shafts.
In such transmissions, the traction rollers are supported on support trunnions which permit pivotal movement of the traction rollers for adjustment of different transmission ratios. A change of transmission ratio may be initiated by slight axial movement of the trunnions, which axial movement out of their center positions causes the traction rollers to climb to different circles of engagement with the toric discs.
It is known to apply axial forces to the trunnions by admission of pressurized fluid from a pressurized fluid source to the piston and cylinder structures disposed at the axial ends of the trunnions. Such arrangements however require hydraulic fluid pumps which are relatively expensive and also relatively heavy. And while such fluid pumps do not add significantly to the cost of a high power transmission, the cost of such pump and its power consumption are quite noticeable in connection with small, low power transmissions as they may be used for example in the drive trains of motorcycles.
Although hydraulic operating mechanisms for the pivot trunnions of traction roller transmissions have proved to function well and reliably, it would be desirable for some applications, particularly for use in low power transmission applications, to have a mechanical trunnion operating mechanism for controlling the transmission ratio.